/Engine/Plugins/Runtime/GeometryProcessing/Source/DynamicMesh/Public/Operations/IntrinsicTriangulationMesh.h
Add new triangle to the mesh topology, does not update any of the intrinsic quantities
int32 AddTriangleInternal ( int32 a, int32 b, int32 c, int32 e0, int32 e1, int32 e2 )